#include <QCoreApplication>
#include <iostream>
using namespace std;
int main()
{
 int A,B,S;
 cout<<"A=";
 cin>>A;
 cout<<"\nB=";
 cin>>B;
 S=0;
 for (int i=0;i<=(B-A); i++)
     S=S+(A+i);
     cout<<"Symma="<<S;
 return 0;
}
